Oh, llys! You're delving...
I think I spent more than 16 hrs/week on average; maybe around 18. 10 hrs per week is probably much enough to go through the study material, proceed with experiments, do some revisions and CMAs (computer marked assignments), etc. TMAs were more demanding. They advise to answer questions along studying relevant parts of books. I usually did everything at once after I finished a whole book. For easier TMAs I needed around 15-20 hrs. For the hardest over 30 hrs. End-of-course assignment took me even more, but it was almost 20% of course value and I had to revised more thoroughly earlier parts of the course.
But everything is relative and it could be easier for you. I did my 'A-levels' 13 yrs ago and apart from some human biology related to my other interests, I had barely touched upon any science over these yrs. I spent ridiculous amount of time polishing answers as I'm not an English native speaker. After all, I wasted hours trying to lay down mathematical calculations and equations using MS Word instead of doing it quickly by hand. I did the same with molecular formulas
I like the 'science enrichment' idea
I was never much interested in geology before, but when I started to look at geological processes with some background in physics and chemistry, several things got really absorbing; I can now spend hours looking at rock fragments on a beach, thinking when and why they were formed. Also speculations about possibility of life on other planets combine loads of topics from remote disciplines and suddenly basic organic chemistry, microbiology and evolution is fusing with physics. I used to (almost) hate cosmology and astronomy, and now, surprisingly, I'm Brian Cox's fan and read academic books in astrophysics
yes, i think it is enriching. After all, it wasn't really hard to get distinction (I'm not very modest
However, deep in heart, anthropology is my 'first love', and I enjoy working with people incomparably more than with stones